1. Field of the Invention
The present invention relates to an embroidery sewing machine having a lower thread winding device, and more particularly to the extracting control of a lower thread remaining in the bobbin of the sewing machine.
2. Description of the Related Art
Conventionally, JP-A-11-342283 has proposed an embroidery sewing machine having a lower thread winding device capable of supplying a lower thread to a bobbin without removing the bobbin from a horizontally rotary hook which comprises a removable embroidering device.
In the embroidery sewing machine having a lower thread winding device, the embroidering device is removably attached to the bed of a sewing machine body and the lower thread winding device is provided under the throat plate of the sewing machine bed. The embroidering device serves to carry out embroidering with a predetermined shape in cooperation with a needle attached to a needle bar while moving an embroidering frame in longitudinal and transverse (XY) directions with a workpiece set to the embroidering frame.
The lower thread winding device is basically constituted by a horizontally rotary hook including, in an outer hook, an inner hook for accommodating a bobbin, a needle bar separating mechanism, a bobbin driving member coupled to the outer hook through a gear, bobbin driving member moving means, a thread hold moving member, and thread holding member moving means.
The lower thread winding device separates the needle bar having a needle attached thereto during the starting operation of the sewing machine to stop the vertical motion of the needle bar and to hold the needle bar above the throat plate by means of a needle bar separating mechanism or an upper shaft crank mechanism during a thread winding operation. On the other hand, the thread holding member moving means is driven by a motor, thereby moving the thread holding member through the thread holding member moving means and causing the tip portion of the thread holding member to abut on the upper flange of the bobbin in the inner hook. The tip portion of the thread holding member holds a lower thread (a thread for the lower thread) led out of a thread piece between a thread position regulating portion and a holding portion engaging a thread end portion, and a thread portion between the thread position regulating portion and the holding portion is pushed against the outer peripheral edge of the upper flange of the bobbin.
Furthermore, the bobbin driving member moving means is operated by the thread holding member moving means, thereby driving the bobbin driving member and coupling the outer hook and the bobbin by the gear through the bobbin driving member. The outer hook is rotated by the rotation of the lower shaft of the sewing machine.
Consequently, when the outer hook is rotated by the driving operation of the sewing machine, the bobbin is rotated (in a reverse direction to the outer hook), and the thread portion of the tip part of the thread holding member pushed against the outer peripheral edge of the upper flange is caught by a slit formed on the upper flange, and the thread portion succeeding thereto is pulled out of the thread piece so that the lower thread is wound upon the central shaft of the bobbin.
In the embroidery sewing machine having a lower thread winding device, however, in the case in which the lower thread wound upon the bobbin is lessened during the sewing operation, the needle is stopped above a workpiece and the embroidering frame is then moved to pull the lower thread out of the back side of a final stitch so that the lower thread remaining in the bobbin is extracted. For this reason, conventionally, there is a drawback that the lower thread cannot be completely extracted from the bobbin if the lower thread remains in a large amount in the bobbin.
It is an object of the invention to provide an embroidery sewing machine having a lower thread winding device which can completely extract a lower thread remaining in a bobbin when the lower thread in the bobbin is gone.
In order to attain the object, as shown in FIGS. 1 and 2, for example, a first aspect of the invention is directed to an embroidery sewing machine 100 having a lower thread winding device 1 for guiding a thread for a lower thread to a bobbin 22 in a hook and for rotating the bobbin 22 to wind the thread thereupon, comprising an embroidering device 240 for making an embroidery on a workpiece S held in an embroidering frame 239 to be moved in X and Y directions,
wherein when the lower thread wound upon the bobbin is lessened, the embroidering frame 239 is moved in a direction of a corner and the lower thread remaining in the bobbin is extra sewn onto a corner of the workpiece S held in the embroidering frame 239 and is thus extracted from the bobbin.
According to the first aspect of the invention, the following functions and effects can be obtained.
(1) Since the lower thread remaining in the bobbin is extra sewn onto the corner of the workpiece, the lower thread can be pulled out in a large amount from the bobbin and can be extra sewn and the lower thread can be completely extracted without a remainder in the bobbin so that the reliability of a lower thread extracting process can be enhanced.
(2) Since the lower thread remaining in the bobbin is extra sewn onto the corner of the workpiece, the extra sewing can be carried out excluding an embroidery to be made on the workpiece. Consequently, the embroidery can be prevented from being damaged by the extracting process based on the lower thread extra sewing operation.
A second aspect of the invention is directed to the sewing machine according to the first aspect of the invention, wherein when the lower thread wound upon the bobbin is lessened, the embroidering frame is moved in the direction of the corner to locate a needle, and is further moved in a direction of another corner.
A third aspect of the invention is directed to the sewing machine according to the first or second aspect of the invention, wherein a size of the embroidering frame is recognized and the embroidering frame is moved in the direction of the corner of the workpiece corresponding to the size of the embroidering frame to locate the needle, thereby carrying out extra sewing.
According to the third aspect of the invention, the embroidering frame is moved corresponding to the size thereof, thereby extra sewing the corner of the workpiece. Therefore, it is possible to execute the extracting process by the extra sewing operation of the lower thread in an amount of movement which corresponds to the size of the embroidering frame and has no waste.
A fourth aspect of the invention is directed to the sewing machine according to the first, second or third aspect of the invention, wherein the extra sewing is performed in a position excluding a position in which embroidering is being carried out or is to be carried out.
According to the fourth aspect of the invention, even if the embroidery reaches the corner of the workpiece, the extra sewing is carried out in the position excluding the embroidery. Therefore, the embroidery can be prevented from being damaged by the extracting process based on the lower thread extra sewing.
A fifth aspect of the invention is directed to the sewing machine according to the first, second, third or fourth aspect of the invention, wherein after the extra sewing is ended, the lower thread is automatically started to be wound.
According to the fourth aspect of the invention, since the lower thread is automatically started to be wound after the extra sewing operation of the lower thread is ended, it is possible to completely automate a work from the operation for extracting the lower thread remaining in the bobbin to the operation for newly winding the lower thread.